Stranding machine

ABSTRACT

In a stranding machine the reels of wire mounted on the machine are braked by hysteresis brakes and the current through these brakes is reduced by the switching of resistors into the brake circuit as preselected numbers are reached in pulse counters for pulses generated by the strand take-up capstan.

United States Patent 1 Schwarz 1451 Apr. 17, 1973 STRANDING MACHINE [75 Inventor: Olek Schwarz, Plainfield, NJ.

[73] Assignee: Anaconda Wire and Cable Company [22] Filed:' Oct. 4, 1971 21 Appl. No.: 185,982

521 US. Cl ..s7/13, 57/19 51 1111.01... ..H0lb 13/o2,no1b 13/08 58 FieldofSearch ..s7/3,10,13-15,

[56] I References Cited I UNITED STATES PATENTS 2,802,328 8/1957 Ritchie ..57/13 Primary Examiner-John Petrakes Attorney-Victor F. Volk ABSTRACT In a stranding machine the reels of wire mounted on the machine are braked by hysteresis brakes and the current through these brakes is reduced by the switching of resistors into the brake circuit as preselected numbers are reached in pulse counters for pulses generated by the strand take-up capstan.

3 Claim, 2 Drawing Figures PATENTED APR 1 7 73 SHEET 1 BF 2 PATENTEB AFR] 71973 Fig. 2

sum 2 or 2 STRANDING MACHINE BACKGROUND OF THE INVENTION In the Cabling of wires to fabricate a cable conductor to be paid into a modern high speed insulation extruder it is essential, for the purpose of maintaining conductor smoothness, to have precisely controlled tension in the strands. For this purpose tension is best applied by braking the strander spools, rather than applying tension directly to the strands, after they have been paid from the spools, since this latter method leaves unresolved the problem of behavior of the portion of strand between the spools and tensioning devices. When braking is applied to the angular rotation of reels, however, its effect on the tension in wire being paid from the reels increases as the reel is emptied. If no correction is made for this progressive increase in tension, as is usually the case in conventional cable making, a cabled strand will have different charac-- teristics at the end of a long run than at the beginning. In the past these subtle differences have been tolerable, but they cannot be tolerated for strands intended to be insulated by precision extrusion. There has also been the problem that braking applied to strand reels while the strander is operating is not appropriate for stopping, when a greater braking power is needed for rapid deceleration and the prevention of slack wire which, upon start up, will form soft spots in the strand.

SUMMARY 1 have overcome the deficiencies of known stranders by braking the reel supports of a strander with hysteresis brakes and automatically not only making a plurality step-wise reductions in the braking power as the reels are paid off but also applying a different sequence of braking actions for stopping than for running.

My new stranding apparatus comprises at least one flyer mounted to rotate on a horizontal axis, a plurality of rotatablereel hub supports mounted on the flyer, gearing means fixed to each of the supports and a like plurality of hysteresis brakes mounted on the flyer,-with means driving each of the brakes from one of the gearing means, so that the brakes retard the rotation of the supports. Slip rings are mounted on my apparatus and are electrically connected to the brakes through an electrical circuit. The slip rings are supplied with current from a source thereof, and my-appara'tus comswitch means, for automatically returning to the original polarity.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 shows a pictorial viewof apparatus made to my invention.

FIG. 2 shows a diagram of an electrical circuit for the apparatus of FIG. 1.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT My stranding apparatus, indicated generally by the I numeral comprises a flyer 11 consisting of a sturdy circular plate rigidly mounted on a heavy horizontal,

conductor 19 the six strands 18 are wrapped around a central strand 23 which passes through the bore of the shaft 12 from a supply 24. The apparatus 10 is suitable for making seven-strand conductor but it will be understood that more than one of the flyers 11 might be mounted on the shaft 12 with strands from the other flyers passing through openings 26 through the flyer wall. Where more than six wires are being wrapped by I the strander the single wire 23 will be replaced by a prises automatic switch means for selectively introducing different current reducing means into the circuit and thereby reducing the current to the'brakes. Different of these automatic switch means are activated by counting means, such as pulsers combined with electromagnetic counters, for counting'length units of strand passing through the strander. Thus, upon preselected increments in the count of length units, tensioning torque applied to the supports is reduced in predetermined steps, as strands are paid from reels mounted on the supports. My apparatus also advantageously comprises means to increase the torque applied by the hub support brakes, upon stopping the apparatus, and thus maintain wire tension. This stopping torque is also automatically reduced in the same predetermined steps as the strands are paid 011'. Switch means are included to reverse the polarity of the brake current to eliminate the salient pole effect of the hysteresis brakes and timing means, initiated by the stranded core in-a known manner. Each of the reel supports 16 has gearing in the form of a timing belt 28 to a small pulley 29 on the shaft of a hysteresis brake 31, such as a Magtrol RN. AB800-3255 brake supplied by Magtrol, Inc. of Buffalo, N .Y. It is an essential feature of my invention to employ hysteresis brakes for the brakes 31 since other braking means such as eddy-current and magnetic particlebrakes will not perform satisfactorily on the heavy duty precision stranding machine of my invention. The amount of torque applied to the pulleys 27 and thus to the reels 17 by the brakes 31 is automatically adjusted by circuit means, hereinafter described, to keep the tension in the strands 18 adjusted as they pay over sheaves 32 along the shaft 12. A cam 33 on the capstan 22 serves as a pulser by momentarily closing a switch 34 (FIG. 2) each time the capstan 22 makes one revolution. The pulses from the switch 34 are'counted by counters 36, 37, 38 such as Durant 49600 counters available from the, Cutler- I-Iammer Co. of Stamford, Conn. Each of the counters is presetfor a different number of pulses determinable from the size of the strand and the size of the reels. Although I have found it economical to employ three separatecounters, it will be understood that a single.

' each full reel run of strand. In the circuit diagram of FIG. 2 slip rings 39 are shown between the brakes mounted on the rotating flyer ll and a panel-mounted electric circuit indicated generally by the numeral 30 in FIG. 2. The slip rings, which are conventional, are not shown in FIG. '1. Each of the brakes 31 receives current in parallel from the slip rings 39, 40 and the following discussion of the operation of one of the brakes will thus apply to all of the brakes mounted on a single Current through the brake 31 determines its torque and is, in turn, determined by the voltage between the slip rings 39', 40. My apparatus comprises fivemeans of adjusting this voltage, readable on a. voltmeter 62-, and thereby adjusting the braking torque and wire tension. These-means comprise variable transformers 41 anclv 42 in the AC portion ofthe circuit supplied from a main power source 46 and resistors 43, 44, 45 in the DC portion of the circuit which is supplied from a bridge rectifier 47. The transformer 41, 42 are accessible to an and contacts 49b, 51c, 52d of these relays are closed. Under these conditions the brake 31 receives the maximum current which has been established for the running tension, supplied from the transformer 41.

When counter 36 reaches a count corresponding to a footage of 2,500 feet (or other preset value) contact 36a closes, energizing relay 49 opening contact 49b and closing contact 49a to switch in the resistor 43 and operator-of the apparatus but the resistors 43, 44, 45

main drive of the stranding apparatus so that when the strander stops the contact 50 closes, energizing a relay coil 48 to close a normally open contact 48b and open a normallyclosed contact 48a. This switches in the variable transformer; 42 for stopping. tension and switches out the running tension transformer 41.

ADJUSTMENT Before the stranding apparatus is started the selector switch 53 is set to adjust contacts 53b so that contact 48a is closed and the running tension of a full reel" is established by adjusting the transformer 41 with the apparatus'station'ary. At this time the footage at which the I counters 36, 37 38 close their respective contacts 36a,

37a, 38a'is reset ifnecessary and the counts are set to zero by means of a gang switch 61. For an example of the counter settings, if the reels 17 hold 10,000 feet the counter 36 is set for 2,500 feet, the counter 37 is set for 5,000 feet,and the counter 38 is set for 7,500 feet. initially the-resistors 43, 44, 45 have been proportionally adjusted to decreasing values of applied resistance. While the apparatus is still stationary the selector switch 53 is moved to run position at contacts 53a. Since contact 50 is closed, relay 48 becomes energized, contact 48a opens and contact 48b closes, switching in the variable transformer 42 the voltage output of which is normally at a value greater than that for the transformer 41 so as to apply a higher stopping tension.

OPERATION When the stranding apparatus 10 starts contact 50 opens and running tension transformer 41 is switched into the circuit. The pulser 34 thenstarts to deliverpulses to counters 36, 37, 38. Prior to the time that counter 36 has reached its predetermined set count point, relays 49, 51, 52 which are in series respectively with the contacts 36a, 37a, and 38a are deenergizeddelay 54 opens the contact 54b, cutting off current. to the relay coil 57 and thereby closing its contacts 57c, 1

time, time delay 54 opens the contact 54a to prevent reduce the current to the brake 31. The apparatus operates at the newreduced braking torque until the count reaches a number equivalent to 5:000 feet (or other preset value). The counter 37 then closes its con-' tact 37a energizing the relaycoil 51, opening the con tacts 51b and 51c and closing contact 51a. This switches in the resistor 44 and switches out the resistor 43, further reducing the current to the brake 31. This brake current remains until the count reaches the value for 7,500 feet (or other preset count) at which time the counter 38 will close the contact 380 to energize relay coil 52, opening contacts 52b, 52c, and 52d and closing contact 52a to switch in the resistor 45 and switch out the resistor 44, still further reducing the brake current until the reel is empty. I 1

When the operation of the apparatus 10 is stopped for some reason before the reels are empty as, for example, when only 3,000 feet of wire has been paid off,

contact 50 closes energizing relay coil 48 to open contact 48a andclose contact 48bswitching in the variable transformer 42 for stopping tension while switching out the running tension transformer 41. Atthis time the counter 36 will already have initiated the introduction of resistor 43 into the circuit as hereinabove described 1 thus proportionally reducing the increased stopping torque.

Hysteresis brakes are known to show the salient pole phenomenon of cogging" upon deenergizing, which may make hand adjustmentof the reels on the flyer dif-' ticult. To obviate this problem I provide a brake off position 53c for selector switch 53 and time delay relays 54, 58 and associated contacts 54a, 54b and 58a. These serve to activatethe relay57 and therebyv its associated contacts 57a, 57b, 57c, 57d. The moment the selector switch 53 is'set to off position 530, relay coil 59 becomes deenergized and contact 59a closes, energizing the time delay coil 54 and relay coil 57 through closed contact 54b. The normally closed contacts 57c, 57d open and the normally open contacts 57a, 57b close, reversing the polarity of the current to the brake 31. After a two second time'interval, however, the time 57d and opening its contacts 57a, 57b. At the same reenergizing the brake 31. After 5 seconds of timethe timer 58 opens its contact 580, resetting the time delay relay 54 and preventing current from reaching the brake 31, so that the reels can be tumed by hand, change in polarization' having removed .the residual magnetism.

When a strand is made up of a plurality of layers the counters 36, 37, 38 and relays 49, 51, 52 may be ap-' plied to a plurality of circuits each having a different set of resistors corresponding to the' resistors 43, 44,45 and slip rings corresponding to the slip rings '39. 1

I have invented a new and useful apparatus of which the foregoing description has been exemplary rather than definitive and for which I desire an award of Letters Patent as defined in the following claims.

I claim:

1. A wire stranding apparatus comprising:

A. at least one flyer mounted to rotate on a horizontal axis,

B. a plurality of rotatable reel hub supports mounted on said flyer,

C. gearing means fixed to each of said supports,

D. a like plurality of hysteresis brakes mounted on said flyer,

E. means driving each of said brakes from one of said gearing means whereby said brakes retard the rotation of said supports,

F. slip rings mounted on said apparatus and electrically connected to said brakes,

G. a source of electric current, v

H. an electrical circuit supplying said current to said slip rings,

I. a plurality of means for reducing the current through said slip rings,

J. automatic switch means for selectively introducing different of said current reducing means into said circuit and thereby reducing said current,

K. means for counting length units of strand passing through said strander, difierent of said switch means being selectively activated by said counting means upon preselected increments automatically returning the count of said length units whereby tensioning torque applied to said supports is reduced in predetermined steps, as strands are paid from reels mounted on said supports.

2. The apparatus of claim 1 comprising means automatically increasing the torque applied by said brakes upon stopping said apparatus.

3. The apparatus of claim 1 comprising switch means reversing the polarity of current supplied to said brakes and timing means initiated by said switch means for automatically returning to the original polarity. 

1. A wire stranding apparatus comprising: A. at least one flyer mounted to rotate on a horizontal axis, B. a plurality of rotatable reel hub supports mounted on said flyer, C. gearing means fixed to each of said supports, D. a like plurality of hysteresis brakes mounted on said flyer, E. means driving each of said brakes from one of said gearing means whereby said brakes retard the rotation of said supports, F. slip rings mounted on said apparatus and electrically connected to said brakes, G. a source of electric current, H. an electrical circuit supplying said current to said slip rings, I. a plurality of means for reducing the current through said slip rings, J. automatic switch means for selectively introducing different of said current reducing means into said circuit and thereby reducing said current, K. means for counting length units of strand passing through said strander, different of said switch means being selectively activated by said counting means upon preselected increments in the count of said length units whereby tensioning torque applied to said supports is reduced in predetermined steps, as strands are paid from reels mounted on said supports.
 2. The apparatus of Claim 1 comprising means automatically increasing the torque applied by said brakes upon stopping said apparatus.
 3. The apparatus of claim 1 comprising switch means reversing the polarity of current supplied to said brakes and timing means initiated by said switch means for automatically returning to the original polarity. 